Electrochemical measuring cell having an ancillary electrode

Abstract

An electrochemical measuring cell is disclosed having a device for sensing an external electical potential. The device is arranged in the region of the outer surface of the diffusion membrane of the cell. The device can be, for example, in the form of a conductive, gas-permeable coating applied to the outer surface of the diffusion membrane.

What is claimed is: 
     
       1. An electrochemical measuring cell comprising: an electrolyte;   a measuring electrode disposed in said electrolyte;   a counter electrode also disposed in said electrolyte;   a housing for holding said electrolyte;   a diffusion membrane for separating said electrolyte from the ambient and having a smooth outer surface facing away from said electrolyte; and,   an electrically-conductive, gas-permeable coating of silver applied to said outer surface for sensing an external electrical potential.   
     
     
       2. The electrochemical measuring cell of claim 1 comprising electric circuit means mounted on said housing for conducting said external potential away from said coating and making the same accessible for measurement. 
     
     
       3. An electrochemical measuring cell comprising: an electrolyte;   a measuring electrode disposed in said electrolyte;   a counter electrode also disposed in said electrolyte;   a housing for holding said electrolyte;   a diffusion membrane for separating said electrolyte from the ambient and having a smooth outer surface facing away from said electrolyte; and,   an electrically-conductive, gas-permeable cotating made of a halogenated compound of silver applied to said smooth outer surface.   
     
     
       4. The electrochemical measuring cell of claim 3, wherein the halogen of said halogenated compound of silver is selected from the group consisting of chlorine, bromine and iodine. 
     
     
       5. The electrochemical measuring cell of claim 3, said coating consisting of chlorinated silver. 
     
     
       6. The electrochemical measuring cell of claim 3 comprising electric circuit means mounted on said housing for conducting said external potential away from said coating and making the same accessible for measurement.